Elastic textured yarn and a process for its production

ABSTRACT

An elastic, low-bulk, textured yarn with a curl count of from 300 to 700 turns per meter, having alternating portions with Stwist and Z-twist, of irregular length.

United States Patent 1191 1 1 3,710,565 Schne'gg et al. 1 Jan. 16, 1973 [54] ELASTIC TEXTURED YARN AND A [56] References Cited ES F PR D PROC S OR ITS 0 UCTION UNITED STATES PATENTS [75] Inventors: Robert Schnegg; Karl-August Hein- 2 H 9 l roth; Herbert Neumann; Rudi 3,337,742 3/1 60 Bur eson ..57/157 [1961 Neu et al...... Busch"; Helm Klaus 3,228,181 H1966 Paterson Nickel, all Of Dormagen, Germany 3,327,463 6/1967 Niina etal.... 3,415,048 12/1968 Welbers [73] Farbenfabr'ke" Amen 3,462,938 8/1969 Mehta ..57/34 gesellschaft, Leverkusen, Germany [22] Filed: Sept, 10, 1970 Primary Examiner-Werner H. Schroeder Attorney-Plumley & Tyner [21] App1.No.: 71,251

[57] ABSTRACT [30] Foreign Application Priority Data An elastic, l0w-bu1k, textured yarn with a curl count of from 300 to 700 turns per meter, having alternating Sept. 16, 1969 Germany ..P 19 46 791.5 portions with s twist and Zmvist, of irregular length [52] 11.8. CI. ..57/l40 R, 57/34 AT, 57/157 TS 51 Int. Cl. ..1)02g 1/02 6 i N0 Drawings [58] Field of Search .57/34 HS, 34 AT, 77.4, 157 TS,

57/157 MS, 157 S, 140 R, 140 BY ELASTIC TEXTURED YARN AND A PROCESS FOR ITS PRODUCTION This invention relates to an elastic, low-bulk, textured endless yarn of synthetic high polymers.

It is known that highly elastic filaments can be obtained by providing the yarn with high twists and using it unfixed, for example in the production of hosiery. Elasticity is obtained in the knitted article as a result of stitch distortion attributable to the tendency of the yarn to twist.

It is also known that a highly elastic crimp yarn can be produced by the more economical false-twist method. In this instance, elasticity is obtained in the knitted article through the longitudinal crimp contraction.

The stitch pattern of the twisted yarn in the knitted article is clear, whilst the stitch pattern of the falsetwist yarn in the knitted article is irregular and mossy in appearance. Unfortunately, the twisting process is very expensive and uneconomical, both in regard to the production of the yarn and in regard to processing on hosiery machines.

It has now been found that a yarn equivalent in ap pearance to the genuinely twisted yarn can be obtained by the false-twist technique. Over its length, the yarn has alternately irregular intervals of genuine S- and Z- twists which, by virtue of their genuine twisting, prevent the yarn from becoming bulky and provide for a smooth appearance in the knitted article, coupled with high elasticity. For special applications, for exam- 'ple circular knitting, and for multifilament processing,

the Z- or S-character has to be emphasized more strongly to guarantee a straight stitch path. Preferred synthetic endless filaments include those of polyamide- 6 or polyamide-6,6. The yarn according to the invention is an elastic, low-bulk, textured endless yarn with a curl count of 300 to 700 turns per meter which has alternating positions with S-twist and Z-twist of irregular length.

The scattering of the genuine twist in the yarn crimped in the S-direction is preferably over 10 to 300 turns per meter, while the scattering of the genuine twist in a yarn twisted in the Z-direction is over 10 to 300 turns per meter. The coefficient of variation is from to and preferably from 7 to 8.

The process for the production of the yarn according to the invention is distinguished by the fact that a filament treated with preparation, consisting of a plurality of single capillaries, of synthetic high polymers (minifil) is false-twist-crimped in its stretched state, the false-twist conditions being adjusted unlike normal machine setting conditions in such a way that the yarn is crimped at rates of from 200 to 900 m/minute under a tension of l to 2 g/dtex and at a temperature of from 150 to 220C.

The twister is designed in such a way that the torque is transmitted to the filament with twisting slip and without any reliable blockage of twist, so that the twists are continuously formed without any regularity by the twister.

This continuous slipping of the genuine twists over tion, and by adjusting the highest possible yarn twist charac-terized by an incipient tendency to curl in the filament, which is under given friction conditions between yarn and twister about 8000 to 10,000 twists per meter. At levels as high as these, the twist can no longer be uniformly distributed. The twist slips through at irregular intervals in the direction of yarn travel and remains locally as a genuine twist in the filament. The yarn is then wound up and mad up on cops in the usual way for further processing. Accordingly, for a residual shrinkage in the textured material of from 6 to 8 percent, a highly elastic, low-bulk yarn is obtained by a false-twist technique which is eminently suitable for the production of elastic knit fabrics.

EXAMPLE 1 An unstretched polyamide-6 filament (dtex 22/3) of three individual filaments is crimped with a friction twister at a rate of 500 meters per minute, under a draft of 230 percent, under a stretching strain of 20 g, with 8,000 twists per minute, at a temperature of 200C, and wound up under a tension of 0.1 g/den. The curl twist amounts to 500 turns per meter, whilst the material has a residual shrinkage of 7 percent.

Curl twisting is determined in the usual way with a conventional twist tester in which a filament loop of definite length is clamped and twisted under specific load. After the swinging yarn has come to rest, the genuine twist of the yarn is determined by means of a known twist gauge or alternatively the swinging process is periodically measured and calculated.

EXAMPLE 2 An unstretched polyamide-6,6 filament (dtex 33/6) of 6 individual filaments is crimped with a friction twister at a rate of 500 meters per minute, under a draft of 230 percent, under a stretching strain of approximately 27 g, with 7000 twists per meter at a temperature of 220C and wound up under a tension of 0.] g/den. The curl twist amounts to 300 turns per meter, and the material has a residual shrinkage of 5 percent.

What we claim is:

1. An elastic, low-bulk, textured yarn having a curl count of from 300 to 700 turns per meter, and having alternating portions of S-twist and Z-twist, of irregular length, said portions of S-twist and Z-twist each having 10 to 300 genuine twist turns per meter.

2. A yarn as claimed in claim 1 wherein the yarn is made from filaments of nylon-6 or nylon-6,6.

3. The yarn of claim 1, said yarn having a residual shrinkage of from 5 to 8 percent.

4. Hosiery consisting essentially of the yarn of claim 1.

5. A process for producing an elastic, low-bulk, textured yarn composed of a plurality of individual high polymer filaments which comprises subjecting said plurality of filaments to the action of a frictional false twisting device at a rate of 200 to 900 meters per minute while'said filaments are being stretched, said filaments being frictionally false twisted by applying at.

least 7,000 to 10,000 turns per meter under a tension of about 0.82 to 2 g/dtex and at a temperature of to 220C., the friction characteristics of said false twisting device being such that twisting slip occurs at irregular intervals at the contact between said yarn and said device.

6. A process as claimed in claim 5 wherein the high polymer is nylon-6 or Nylon-6,6. 

1. An elastic, low-bulk, textured yarn having a curl count of from 300 to 700 turns per meter, and having alternating portions of S-twist and Z-twist, of irregular length, said portions of Stwist and Z-twist each having 10 to 300 genuine twist turns per meter.
 2. A yarn as claimed in claim 1 wherein the yarn is made from filaments of nylon-6 or nylon-6,6.
 3. The yarn of claim 1, said yarn having a residual shrinkage of from 5 to 8 percent.
 4. Hosiery consisting essentially of the yarn of claim
 1. 5. A process for producing an elastic, low-bulk, textured yarn composed of a plurality of individual high polymer filaments which comprises subjecting said plurality of filaments to the action of a frictional false twisting device at a rate of 200 to 900 meters per minute while said filaments are being stretched, said filaments being frictionally false twisted by applying at least 7,000 to 10,000 turns per meter under a tension of about 0.82 to 2 g/dtex and at a temperature of 150* to 220*C., the friction characteristics of said false twisting device being such that twisting slip occurs at irregular intervals at the contact between said yarn and said device.
 6. A process as claimed in claim 5 wherein the high polymer is nylon-6 or Nylon-6,6. 